Rotor for axial flow elastic fluid compressors or turbines



Jan. 29, 1952 F. E. 6STMAR ROTOR FOR AXIAL, FLOW ELASTIC FLUID COMPRESSORS OR TURBINES Filed July 13, 1949 Patented Jan. 29, 1952 ROTOR FOR AXIAL FLOW ELASTIC FLUID COMPRESSORS OR TURBINES ..Frans.Eric Ossian Ostmar, .Finspong, Sweden, assignor to .Svenska Turbinfabriks Aktiebolaget Ljungstriim, joint-stock company Finspong,

Sweden, a Swedish Application July 13, 1949, Serial No. 104,561 In Sweden September 22, 1948 i 1 Claim.

.The present invention relates to axial flow elastic fluid machines, as compressors and turbines of the rotary. type and more particularly to the rotors of such machine. i

The object of .the invention is to provide a rotor of such a small weight and of such a great strength as to be fit for use in connection with turbines and compressors of jet propulsion units for aeroplanes.

The rotor according to the invention is built up of axial sections comprising discs having two or more axially extending cylindrical or substantially cylindrical flanges on one side or on each side, said discs being held together axially so as to form a unit by means of a central bolt, by means of which the discs are jammed together with a sufiicient power to cause the abutting flanges of the discs to act as a unitary tubular shaft for the rotor.

According to another feature of the invention the connecting bolt is tubular and provided at one end with an abutment for fixing its axial position with relation to one end section of the rotor and provided with means at its other end for engagement with the other end section of the rotor or a member connected therewith, in order thereby to permit a jamming of the sections in the axial direction.

The use of a tubular bolt for jamming the sections together reduces the total Weight of the rotor, while at the same time allowing a central, preferably also tubular, bolt to extend through the first mentioned tubular bolt for connecting the rotor to the rotor of another axially spaced machine, as for instance, for connecting the rotor of a compressor to the rotor of a turbine for driving the compressor.

According to a further feature of the invention the said last-mentioned means comprises a threaded portion of the bolt, allowin a jamming of the discs by turning the bolt.

According to still another feature of the invention the abutting flanges of the discs are located on a small radius as compared with the outer radius of the discs, other axial flanges being provided at or near the outer periphery of the discs which are adapted after the sections are jammed together to be rigidly connected together, as by welding.

The above mentioned and other features of the invention will more clearly appear from the following description with reference to the accompanying drawing which shows a substantially diagrammatic axial section of one half-part of a.

machine having a rotor according to the invention and which is hereinafter referred to as a compressor.

In the drawing th numeral 1 indicates the casing of the machine, 2 is the intake for the fluid (as air) to be compressed, and 3 is a transi-.

tion passage leading to a combustion chamber indicated in the drawing by portions of its casing shown to the right of the passage 3. Secured to the inside of the casing l are guide blades 4. The moving blades 5 of the compressor which are arranged alternately with the guide blades are carried by a rotor comprising a plurality of axial sections, preferably, as shown, so that each section carries an annular set of moving blades.

Each section of the rotor consists of a thin disc 6 provided between its inner and outer peripheries with a flange 1 on one side or both sides and havingfurther, near its outer periphery, at a distance from the respective set of blades, another flange or fiangess. The flanges l and 8 are, preferably, cylindrical so that in the assembled state of the rotor they may act as two concentric cylinders.

Extending through the hub portions of the discs 6 is a tubular bolt 9. Said bolt carries at its one end (that is to say, the right hand one in the rawing) an external collar (0 and is formed with a threaded portion II at its other end. Bearing against said collar H) is an internal collar 12 provided near the outer end of a conical sleeve 13 widened towards its inner end where it bearsv against a flange 1 of the adjacent end section of the rotor. The opposite threaded end of the tubular shaft 9 is screwed (at H) into a threaded boring of a conical sleeve l4 rigidly connected at its outer end to a shaft 5 for transmitting the starting torque to the rotor and bearing at its inner, wider end against a flange 1 of the respective end section of the rotor.

By tightening the tubular bolt 9 the rotor sections may be jammed between the members 13- and M'with such a power as to cause the flanges 1 to tightly abut against each other and behave like a tubular shaft rigidly connected to the tubular bolt 9 through the intermediuln of the end members l3 and M. In order to improve the connection between the rotor sections the flanges 8 may be welded together, as indicated at (6. To allow turning of the tubular bolt 9 by means of a key the bolt is provided with a head I! outside the collar I 0.

The end members I3, 14 of the composite tubular shaft represented by the flanges 1 are rotatably mounted in the stationary frame of the machine by means of ball bearings l8 and I 9, respectively, so that they may act as journals for said shaft and thus for the rotor.

Owing to the small wall thickness and the great length of the tubular bolt 9 it is impossible merely by mechanical means, that is to say, meree 1y by screwing the bolt into the member [4, to effeet, a sufficiently strong jamming together of the rotor sections.

According to, the'invention this jamming operation is effected by first tightening the tubular bolt 9 as far as possible by turning it by means of a key, then heating the bolt until a predetermined extension thereof is obtained and, finally, again tightening the bolt as far aspossible. The heating can be effected by means of a hot fluid, as hot air, oil or steam, which is passed through the bolt, or by electric heating, as for instance, according to the dip heating method. The extension obtained by heating the bolt may be measured by means of a suitable gauge 20. After the second tightening operation the tubular bolt is allowed to cool and contract. The tensile strain may be. measured and controlled by a suitable tension meter 2|, constructed, for instance, according to the so called strain-gagemethod, that is to say, with the use of a pasted electric resistance wire. a

In order to connect the described rotor to the rotor of an adjacent coaxial machine, as for coupling together the rotor of a compressor and the rotor of a turbinev for driving the compressor a, preferably, tubular bolt 22 extending through the tubular bolt 9 may be used. To this end said bolt 22 is fixed axially at its one end with relation to the bolt 9 by means of an external collar.

23 of the bolt 22 bearing against an internal col- 1ar'24 of shaft 15, while the other end of the bolt 22 is'screwed into an internally threaded flange 25 of a connecting member 26 provided between the rotor of the compressor and the turbine rotor which may be bolted to the turbine rotor, as indicated. Tightening of said bolt 22 may be effected in the way already described in connection with the description of the tubular bolt 9.

Inserted between the rotor of the compressor and the transition element 3 is a device, indicated as a whole at 21, for balancing the axial thrusts.

In order that the collars I0 and 23 of the bolts 9 and 22, respectively, may not be in the way of each other, they are located at opposite ends of the compressor rotor.

What I claim is:

A multi-section rotor for elastic fluid machines of the axial flow type, comprising in combination, a set of axially spaced discs for constituting the sections of the rotor, concentric axial flanges located at a small diameter on said discs for abutting against each other in the assembled rotor so as to form a composite tubular shaft therefor, other concentric axial flanges provided at a greater diameter of the discs for efiecting a rigid connection between adjacent discs,'sleeveshaped conical end portions connected at their wider ends to opposite ends of the tubular shaft formed by the said first-mentioned flanges, said conical portions being shaped at their smaller ends as journals a tubular bolt extending centrally through said tubular shaft and associated journals, abutments on one end of said bolt for engaging with one of said journals and a screwthread at the other end of said bolt for engaging with the other journal for allowing jamming of the set of discs by turning the bolt, another bolt extending centrally through said first-mentioned structure in order to prevent interference with.

one another.

FRANS ERIC OSSIAN GSTMAR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,213,940 Jendrassik Sept. 3, 1940 2,241,782 Jendrassik May 13, 1941' 2,369,051 Huber Feb. 6, 1945 2,452,732 McLeod Nov. 2, 1948 2,479,056 Bodger Aug. 16, 1949 2,483,616

Bergstedt Oct. 4, 1949 

